1. Field of the Invention
The present invention relates to an image reading apparatus and method of continuously scanning an original by sequentially turning on a plurality of light sources, i.e., light sources of three primary colors R, G, and B, thereby performing color separation, and a computer-readable storage medium.
2. Related Background Art
As shown in FIG. 11, a conventional image reading apparatus for performing color separation by using a plurality of light sources, i.e., light sources of three primary colors R, G, and B, performs color separation by continuously scanning an original by moving a reading unit while sequentially turning on the light sources in synchronism with a read start pulse (Hsync) having a fixed period.
This conventional apparatus, however, scans an original by moving the reading unit while sequentially turning on the light sources. Therefore, in the process during which colors are switched by the sequential turn-on operation, the irradiation position of the original moves over time. This produces color misregistration when color separation is performed and thereby lowers the quality of image read.
It is an object of the present invention to reduce color misregistration and improve image quality.
To achieve the above object, an image reading apparatus according to the present invention comprises a plurality of light source means for emitting light components of different colors to illuminate an original, control means for allowing the light source means to sequentially emit light components only for respective predetermined emission times such that emission times of light source means other than a predetermined light source means are set close to an emission time of the predetermined light source means in a time-series manner, and photoelectric conversion means for reading an image on the original illuminated by the light source means and outputting an image signal while moving relative to the image.
With this arrangement, the time differences produced when the light sources are sequentially turned on can be reduced. Consequently, it is possible to reduce color misregistration caused by the differences between the irradiation positions of an original and improve the image read quality.
Other objects, features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.